This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-278219, filed Sep. 30, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to an antenna capable of capturing and tracking a plurality of communication satellites at once, which is employed on a ground station of a satellite communication system.
At the present, about 200 communication orbiting satellites are being launched on the earth, and it is possible to communicate with, at least, some satellites from any point on the earth. As a satellite communication system using these communication orbiting satellites, an iridium system and a sky-bridge system are proposed and being developed for practical use.
In this satellite communication system, since an orbiting satellite passes the empyrean in ten minutes or so, it is necessary to sequentially switch a satellite of the communication party in order to establish a sequential communication in the ground station. Therefore, a plurality of antennas capable of capturing and tracking communication orbiting satellites must be prepared in the ground station. While one antenna is tracking one satellite and communicating with the same satellite, another antenna starts capturing and tracking another orbiting satellite and switches the communication party before failing in communication with the former satellite.
In the conventional antenna capturing and tracking an orbiting satellite, a parabola-typed or phased array-typed antenna portion is mounted on a driving control mechanism for rotating the antenna portion around the azimuth axis, or elevation axis. This driving control mechanism turns the antenna portion in accordance with the movement of a satellite of the communication party, thereby directing the antenna beam toward the direction of the satellite.
The above-mentioned satellite communication system employs a plurality of the above-mentioned antennas as the facilities of the ground station, and it is necessary to locate each antenna not to block each antenna beam. For example, when locating two parabolic antennas each having the round reflex mirror of 45 cm diameter, it is necessary to locate them at a distance of about 3 m, in order not to block each beam in the horizontal direction.
Thus, a large space is required in order to set a plurality of antennas, and it is extremely difficult to set them in a general domestic site or house. Therefore, an antenna that can track a plurality of communication satellites and that can be set compactly in a relative small space is desired, in order to spread the satellite communication system into a general domestic use when starting the operation of the satellite communication system. Further, an easily manufacturing and assembling method is desired in the manufacture of the antenna.
As mentioned above, the conventional orbiting satellite capturing and tracking antenna can track only one satellite. Therefore, it is necessary to use a plurality of antenna in order to capture and track a plurality of communication orbiting satellites at once. In this case, each antenna must be positioned at a good distance not to block each other, thereby requiring a large space for installation. Thus, an antenna that can capture and track a plurality of communication satellites and that can be set compactly in a relative small space is desired, in order to spread the satellite communication system widely. Further, an easily manufacturing and assembling method of the antenna is desired in the manufacturing process of the antenna.
An object of the present invention is, in order to realize the above requirements, to provide a method of manufacturing and assembling the antenna at ease improved in electrical property, when providing an antenna that can capture and track a plurality of communication orbiting satellites at once and that can be set compactly in a relative small space.
In order to solve the above problems, an antenna related to the present invention comprises a spherical lens for concentrating electronic waves; a plurality of transmitting and receiving modules of moving independently at a substantially constant distance from a bottom hemispheric surface of the spherical lens; a driving unit for moving the plurality of transmitting and receiving modules to arbitrary positions; and a radome for covering at least a top hemispheric surface that becomes an electric beam forming surface of the spherical lens, in which a foaming material layer is interposed to integrate the spherical lens and the radome and the radome is adopted to support the spherical lens.
According to the above configuration, since a plurality of power supplying portions can be arranged on one spherical lens, the antenna can track a plurality of communication satellites and it can be set in a small space. Furthermore, since it is unnecessary to provide a supporting member for supporting the spherical lens in the main body of the antenna, the antenna can be made more compact. In addition, since the supporting member is not required, wave beam is prevented from being disturbed by the supporting member and it is made possible to swing wave beam up to a low wave angle, so that it becomes possible to enlarge an allowable range of a plurality of power supplying devices over the whole area of a spherical lower face of the spherical lens.
The foaming material is formed of material having a dielectric constant lower than that of the spherical lens. Thereby, influence on radio wave beam can substantially cancelled.
A plurality of concave portions and a plurality of convex portions to be fitted to (be engaged with) each other in a depth much smaller than the wavelength of radio wave beam are formed at least on one side, between the spherical lens and the foaming material layer and between the foaming material layer and the radome. According to this structure, joining strength between the spherical lens and the foaming material layer or between the foaming material layer and the radome can be increased without affecting radio wave beams.
In a method for integrally forming a spherical lens and a radome for the antenna, foaming material is filled in a space between the spherical lens and the radome in a state where the spherical lens and the radome are positioned. According to this method, since the spherical lens and the radome can be formed in an integral manner, for example, at an installation place of the antenna, the transportability of respective parts of the antenna is improved, it is made easy to assemble the antenna, and working in site is made easy.
In an assembling method, after the spherical lens is positioned in a state where the radome is reversed, foaming material is filled between the spherical lens and the radome so as to integral them with each other, and the radome is fixed at a predetermined portion of the main body. According to this method, filling work is made easy.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.